[C++] Move arrow::ArrayData to a separate header file

[asfimport]

There are code modules (such as compute kernels) that only require ArrayData for doing computations, so pulling in all the code in array.h is not necessary. There are probably other code paths that might benefit from this also.

Reporter: Wes McKinney / @wesm
Assignee: Wes McKinney / @wesm

Related issues:

• [C++] C++ array kernels framework and execution buildout (umbrella issue) (relates to)

_{Note: This issue was originally created as ARROW-8966. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
This was resolved in 94a5026